The present invention relates to polymer blend compositions containing polyamides (also called PA for short) and/or block copolyester amides, aliphatic polyketones (also called PK for short) and optionally customary auxiliaries and additives. The invention also relates to the preparation of these polyamide/polyketone (PA/PK) blend compositions.
It is known from the organic chemistry of low-molecular-weight compounds that molecules which contain ketone groups can react with each other. This reaction, which can proceed in both base- and acid-catalysed forms, is called aldol condensation. Since polyamides contain both acid COOH-- and basic amino end-groups, the possibility exists that polyketones are crosslinked by the addition of polyamides. In kneading tests in which mixtures of polyketone and amino- or carboxyl-terminated PA 12 were studied, it was shown that the crosslinking of polyketones is caused mainly by the amino end-groups of the polyamide.
Blends made from linear alternating polymers comprising CO and olefins and impact-modified PA6/ABS blends are described in EP-A-057 374. These systems are morphologically complex systems which necessarily contain rubber-like portions. This rubber portion can lead to the reduction of the dimensional stability in heat. The yield stress is also reduced, as described in the examples.
PK/PC blends in which graft polymers comprising PC and PA6 act as compatibilizers are described in Statutory Invention Registration H1601. However, there is still no increase in impact strength when this graft polymer is added at the rate of 5%.
Ternary polymer blends comprising PK, PA and maleic anhydride-grafted block copolymers are described in U.S. Pat. No. 5,175,210. According to this teaching, however, PAs are used at the rate of up to 20% as compatibilizers. If greater proportions of PA are to be achieved for the PA/PK blends, SEBS block copolymers are necessary as compatibilizers.
PK/PA blends in which the polyamide has a molar mass of at least 5000 g/mol are described in U.S. Pat. No. 4,839,437. The polyamides contained in the PK/PA blends have too high a concentration of amino end-groups, which leads to crosslinking reactions (cf. col. 5, 11. 24-26).
U.S. Pat. No. 4,874,825 describes PK/polyether ester amide blends where the molar mass of the polyether ester amide is likewise limited (15,000 g/mol).
Ketone resins are unsaponifiable and neutrally reacting resins (synthetic resins), with a bright colour and softening ranges of ca. 80-130.degree. C., which result from the alkaline-catalysed self-condensation of ketones (cyclohexanone, methylcyclohexanone) or mixed condensation of ketones (acetone, butanone, acetophenone, cyclohexanone, methylcyclohexanone) with formaldehyde. Mixed condensates of ketones (e.g. cyclohexanone) with longer-chained aldehydes are not of industrial importance. Depending on the starting ketone, the ketones are divided into acetone, acetone phenone resins etc. Ketones comprising mixtures of different ketones are also known.
Polyketone polymers are known in the state of the art. For example, U.S. Pat. No. 4,880,903 describes linear alternating polyketone terpolymers on the basis of carbon monoxide ethylene and other olefinically unsaturated hydrocarbons, such as propylene.
U.S. Pat. No. 4,843,144 describes a process for the preparation of linear alternating polyketone polymers comprising carbon monoxide and at least one ethylenically unsaturated hydrocarbon using palladium catalysts.
Other aliphatic polyketones on the basis of ethylene, carbon monoxide and propylene are described e.g. in EP-A-457 374 and EP-A-569 101 and are supplied to the market under various trade names.
It is clear from the documents mentioned above that it was not previously possible to prepare pure PK/PA blends over the whole composition range without limiting the PA molar mass. Also, the compounding of these blends was difficult, as there was the risk of crosslinkings or decomposition.
The object was therefore to provide PA/PK blends whose composition covers the whole concentration range, which possess viscosities matched to the different processing methods without crosslinking or decomposition reactions occurring during preparation.
This object is achieved according to the invention by the polymer blend composition according to Claim 1 and by the process according to Claim 11 or 12 and by the uses according to Claim 13.
Advantageous versions of the invention are contained in the dependent claims.